JPH0357928A - Light information detector - Google Patents

Abstract

PURPOSE:To obtain a detector which achieves a higher detection sensitivity and a higher S/N ratio with a simple construction by a method wherein irradiation light transmitted through a lens barrel is condensed with a lens to irradiate a light information recording medium through a light incoming/outgoing hole. CONSTITUTION:This apparatus is provided with a light incoming/outgoing hole 3 provided at the tip of a lens barrel 1 and a spherical lens 2 to condense light incident into or emitted from the lens barrel 1 through the light incoming/ outgoing hole 3. Irradiation light transmitted through the lens barrel 1 is con densed by the lens 2 and made to irradiate a light incoming/outgoin hole 3. Detection light emitted or reflected from the medium 9 is made incident at the light incoming/outgoing hole 3 and condensed with the lens 2 to be intro duced to a photodetector 7. An inner circumferencial surface of the light incoming/outgoing hole 3 is formed as mirror surface which reflects the detec tion light emitted or reflected from the medium 9 to be introduced into the lens barrel 1 thereby achieving a higher detection sensitivity or a remarkably higher S/N ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical information detection device that can be used, for example, in an image detection section of a radiation image reading device.

[Prior Art] For example, a radiation image reading device is used to read a radiation image accumulated as a latent image on a stimulable phosphor plate.

This radiation image reading device reads the radiation image by detecting fluorescence generated corresponding to the latent image when excitation light is irradiated to each position of the stimulable phosphor plate and performing image processing on the fluorescence. It's easy to understand.

In this radiation image reading device, excitation light emitted from a light source such as a laser device is focused and irradiated onto each point of the stimulable phosphor plate, and the irradiation of the excitation light causes the fluorescence generated from each of these points to be emitted. An optical information detection device is used that focuses the light and guides it to a photodetector.

This optical information detection device has a light input/output hole at the tip of the lens barrel that transmits excitation light as irradiation light and fluorescence as detection target light, and the input/output hole is provided near the light input/output hole. It is equipped with a lens such as an aspherical lens that focuses the light entering and exiting from the hole. In other words, the light that can enter and exit the lens barrel through the light input/output hole is narrowed down to the necessary minimum, so that when irradiation light such as the excitation light is irradiated, a part of this irradiation light may accumulate. Scattered light is generated by being scattered by an optical information recording medium such as a fluorescent plate, and this scattered light is reflected by the lens and enters the optical information recording medium again, causing harmful effects such as exciting other parts that are not intended. This makes it possible to accurately detect optical information.

[Problems to be Solved by the Invention] Incidentally, in the optical information detection device as described above, in order to increase the detection sensitivity, it is necessary to detect light emitted or reflected from the optical information recording medium such as the stimulable phosphor plate. It is necessary to make as much of the target light as possible enter the lens and guide it to the photodetector. For this reason, the tip of the lens barrel is brought as close as possible to the optical information recording medium, and a lens with as large an aperture ratio as possible is used as the lens.

However, since it is necessary to scan each point on the optical information recording medium with the tip of the mirror, it is necessary to separate the tip of the lens barrel from the optical information recording medium by a distance necessary for this scanning. Additionally, there is a certain limit to the aperture ratio of the lens. Furthermore, the size of the light entrance/exit hole must be made small enough to prevent the problem that the scattered light of the irradiation light is reflected by the lens and enters the optical information recording medium again. For this reason, out of the detection target light emitted from one point on the optical information recording medium, the amount of light that can be taken into the lens barrel through the light entrance/exit hole is extremely limited. the result,
There has been a certain limit to the improvement of detection sensitivity or S/N ratio.

The present invention has been made against the above-mentioned background, and provides an optical information detection device that can significantly improve detection sensitivity or S/N ratio with an extremely simple configuration. It is intended for this purpose.

[Means for Solving the Problems] The present invention solves the above problems by having the following configuration.

The lens barrel includes a lens barrel, a light input/output hole provided at the tip of the lens barrel, and a lens that focuses light entering and exiting the lens barrel through the light input/output hole. The irradiation light transmitted through the lens is focused by the lens and irradiated onto the optical information recording medium through the light input/output hole, and the detection light emitted or reflected from the optical information recording medium by the irradiation of the irradiation light is detected. In the optical information detection device, the light enters through the light input/output hole, is focused by the lens, and is guided to the photodetector through the lens barrel, wherein the inner circumferential surface of the light input/output hole is used for recording the optical information. The structure is characterized by a mirror surface that reflects the detection light emitted or reflected from the medium and guides it into the lens barrel.

[Operation] According to the above structure, the irradiation light transmitted through the lens barrel is focused by the lens and irradiated onto the optical information recording medium through the light input/output hole.

As a result, detection light is generated by emission or reflection corresponding to the information recorded on the optical information recording medium.

This detection light enters through the light entrance/exit hole, is focused by the lens, and is guided to the photodetector through the lens barrel.

In this case, conventionally, out of the detection light emitted from one point of the optical information recording medium, the light taken into the lens barrel is connected to a circle indicating the effective diameter of the lens and a circle from which the detection light is emitted. A conical area that is shaped when you connect the points (
It was limited to light within the solid angle (hereinafter referred to as the solid angle that takes into account the effective diameter of the lens).

In contrast, in the above-mentioned structure, the inner circumferential surface of the light input/output hole is a mirror surface that reflects the detection light emitted or reflected from the optical information recording medium and guides it into the lens barrel. , when the light that enters the lens barrel out of the detection light emitted from one point of the optical information recording medium connects the circle indicating the lower limit of the mirror surface and the point from which the detection light is emitted. (hereinafter referred to as the solid angle looking into the lower limit of the mirror surface). That is, if the light incident
Even if the diameter of the exit hole is the same as before, this light input and
Conventionally, by making the inner circumferential surface of the light exit hole a mirror surface to reflect the detection light and guide it into the lens barrel, the light is blocked by the inner circumferential surface of the light input/output hole and the detected light is reflected and guided into the lens barrel. Most of the detection light that could not reach the lens barrel can be introduced into the lens barrel. In other words, the range of detection light that can be introduced into the lens barrel is not limited to the solid angle that takes into account the effective diameter of the lens, but depends on the solid angle that takes into account the lower limit of the mirror surface. Here, the solid angle at which the mirror surface is viewed can be made significantly larger than the solid angle at which the lens is viewed. Therefore, the amount of detection light taken into the lens barrel can be significantly increased compared to the conventional method.

[Embodiment] FIG. 1 is a diagram showing an optical information detection device according to an embodiment of the present invention, and FIG. 2 is a partially enlarged view of FIG. 1.

Hereinafter, one embodiment will be described in detail with reference to these drawings. Note that this embodiment is an example in which the present invention is applied to a radiation image reading device.

In the figure, 1 is a lens barrel, 2 is an aspherical lens, 3 is a light entrance/exit hole, 4 is a mirror surface, 5 is a total reflection mirror, 6 is a dichroic mirror, and 7 is a photodetector , 8 is a laser oscillation device, and 9 is an optical information recording medium.

The lens barrel 1 is made of aluminum or other metal and has a substantially cylindrical shape, and the upper end in the figure is open. On the other hand, the lower end in the figure, that is, the tip of the lens barrel 1, is substantially shielded by the shielding portion 1a. This shielding part 1a has an outer shape that roughly follows the shape of a truncated cone with its apex pointing downward in the figure, and a light input/output hole, which is a through hole, in the center of the truncated part. 3 is provided.

The inner circumferential surface of the light input/output hole 3 has a tapered cross-section so that the inner diameter increases as it goes upward in the figure, and the surface is mirror-finished so that a mirror-finished portion 4 is formed.
It is composed of

Further, an aspherical lens 2 is disposed above the light entrance/output hole 3 of the lens barrel l, and an aspherical lens 2 is mounted on the pedestal tb. 1b (Fig. 2).

This aspherical lens 2 is connected to one point 9 of the optical information recording medium 9.
The direct light 1d emitted from the point 9a and directly incident on the aspherical lens 2 is made into parallel light, and the reflected light 1 emitted from the one point 9a and reflected by the mirror surface portion 4 is focused, and both of them are collimated. Introduce into cylinder 1. At the same time, laser light 1o, which is excitation light, is introduced from the upper opening of the lens barrel (2) and is focused on a point 9a of the optical information recording medium 9 through the light input/output hole 3.

Note that the direct light fId and the reflected light Dr are detection lights that are detection targets for detecting optical information.

The total reflection mirror 5 has a cylindrical shape and has a mirror-finished inner circumferential surface, and is housed on the inner circumferential surface of the lens barrel 1, and reflects the reflected light 1 to reflect the reflected light 1. It functions to emit light to the outside from the upper opening of the lens barrel 1.

The dichroic mirror 6 is connected to the laser oscillation device 8.
Laser light 1 emitted from. On the other hand, the detection light emitted from the lens barrel 1. l! d and. I! , is reflected and guided to the photodetector 7.

The photodetector 7 is, for example, a photomultiplier tube.

Further, the laser oscillation device 8 includes the optical information recording medium 9
The optical information recording medium 9 oscillates a laser beam having an appropriate wavelength so that detection light corresponding to the optical information recorded on the optical information recording medium 9 can be obtained by irradiating the optical information recording medium 9 to the optical information recording medium 9.

The optical information recording medium 9 is a well-known stimulable fluorescent plate,
For example, an X-ray diffraction image is accumulated as a latent image by an X-ray diffraction device, and when the optical information recording medium 9 is irradiated with excitation light having a certain wavelength, fluorescence corresponding to the latent image is emitted. It is something that occurs.

In the above-mentioned ellipsoid, the laser beam 1o emitted from the laser oscillation device 8 passes through the lens barrel 1 and enters the aspherical lens 2, and due to the action of the aspherical lens 2, the light enters and exits. The light is focused through the hole 3 to a point 9a on the optical information recording medium 9. As a result, if a latent image is accumulated at the point 9a, fluorescence is generated from the point 9a corresponding to this latent image. This fluorescent light is transmitted directly through the light input/output hole 3 or reflected by the mirror surface portion 4 on the inner circumferential surface of the light input/output hole 3 to become direct light 1d or reflected light 1, respectively, and become the mirror light 1d. It is introduced into the cylinder 1.

In this case, since the direct light 1d is a thousand line light, it travels straight through the lens barrel 1, exits from the upper opening of the lens barrel 1, is reflected by the dichroic mirror 6, and is detected by the photodetector. 7.

On the other hand, since the reflected light 1r is light with a slight focusing effect, it is once reflected by the total reflection mirror 5 within the lens barrel 1, and is emitted to the outside through the upper opening of the lens barrel 1. Further, the light is reflected by the dichroic mirror 6 and enters the photodetector 7.

Thereby, the light emitted from one point 9a of the optical information recording medium 9 is detected by the photodetector 7. Therefore, the surface of the optical information recording medium 9 is scanned by the above-mentioned optical information detection device, and the optical information at each point of the optical information recording medium 9 is detected by the photodetector 7. By applying predetermined processing using an image processing device or the like, information such as an X-ray diffraction image can be read.

Here, now, the distance h1 between the tip of the lens barrel l and the optical information recording medium 1 is 0.5111111, and the light incidence
r2=5. 74tnlφ, the light input/output hole 3
The distance h2 between the portion showing the maximum inner diameter of the optical information recording medium 9 and the optical information recording medium 9 = 6,001! III, and when the light emitted from one point 9a of the optical information recording medium 9 that is introduced into the lens barrel 1 and detected by the photodetector 7 is expressed as a solid angle, the solid angle in this case is θ1=126°.

This corresponds to approximately 55% of the total amount of light emitted from one point 9a of the optical information recording medium 9, that is, the amount of light emitted over the entire solid angle range of 180°.

On the other hand, when the inner circumferential surface of the light entrance/output hole 3 is not made into a mirror surface as in the past, and the same dimensions as above are adopted, the light introduced into the lens barrel 1 is solid angle θ. =86°, which is about 27% of the total amount of light emitted from the point 9a.

In this way, according to the embodiment, simply the light input
By making the inner peripheral surface of the emission hole 3 a mirror surface, which is extremely simple, the detection sensitivity or S/
The N ratio can be significantly improved.

In addition, in the above-mentioned embodiment, an example was given in which the present invention was applied to an image detection section of a radiographic image collection device, but the present invention is not limited to this, and can be applied to, for example, an optical disc, etc. .

In addition, in the above-mentioned embodiment, an example was given in which the inner circumferential surface of the light input/output hole was mirror-finished to make the inner circumferential surface of the light input/output hole a mirror surface. For example, a well-known total reflection film may be formed on the inner peripheral surface of the light input/output hole.

[Effects of the Invention] As detailed above, the present invention is capable of detecting light emitted from or reflected from an optical information recording medium by using the inner circumferential surface of the light input/output hole provided at the tip of the lens barrel. By using an extremely simple structure in which the mirror surface reflects light and guides it into the lens barrel, an optical information detection device is obtained that makes it possible to significantly improve detection sensitivity or S/N ratio. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing an optical information detection device according to an embodiment of the present invention, and FIG. 2 is a partially enlarged view of FIG. t. ■... Lens barrel, 2... Aspherical lens, 3... Light entrance...
Output hole, 4... Mirror surface section, 5... Total reflection mirror, 6...
Dichroic mirror, 7... Photodetector, 8... Laser oscillation device 9... Optical information recording medium.

Claims (1)

[Scope of Claims] A lens barrel, a light input/output hole provided at the tip of the lens barrel, and a lens that focuses light entering and exiting the lens barrel through the light input/output hole. The irradiation light transmitted through the lens barrel is focused by the lens and irradiated onto the optical information recording medium through the light input/output hole, and the irradiation of the irradiation light causes light to be emitted or reflected from the optical information recording medium. In the optical information detection device, incoming detection light enters the light input/output hole, is focused by the lens, and is guided to the photodetector through the lens barrel, comprising: an inner circumferential surface of the light input/output hole; An optical information detecting device characterized in that: is a mirror surface that reflects detection light emitted or reflected from the optical information recording medium and guides it into the lens barrel.